Is this an installation problem in that case? It worked fine before... Could the card have been moved for some reason just a couple of millimeters or something because of vibration? Where should I start so?

Well, it was something totally unexpected! It is a process of a little and extremely handy program called "Everything", which is FAST as nothing else to search files in Win 7. Well, who knows how this happened, but even after uninstalling "Everything", the process is still somewhere, so we have to boot up the system, then close Pulsar and then start it again, and it works fine. I will find what is going on hopefully.